The present invention relates to a system for anchoring traction elements of a flexible tubular structure to the opening in a rigid wall, with the anchoring being achieved by pressing axially on a shoulder or flange after passage through an opening provided in the rigid wall. In this description, to simplify the disclosure of the invention, the term "sleeve" will be used to define the flexible annular structure and the term "bead" will define the end of the sleeve which has a larger diameter than that of the sleeve and which abuts the rigid wall, hereinafter called "mating flange".
Sleeves with a flexible bead are known wherein the bead generally has an internal armature, i.e. embedded in the rubber, of annular form, composed of high-modulus rubber, a textile ply, a textile or metal strand, or a flexible spring. This type of reinforcement is adopted to render the bead deformable to permit mounting mating flanges after manufacture of the sleeve, by forcing the bead through the bore. The major drawback of these systems is the requirement of pinching of the flat flange between two planes, according to the device adopted, for example, by the Societe Kleber Industrie for its Dilatoflex NT expansion sleeves (technical dossier 79-BA1), or by the use of a form, obtained by machining, for a rigid part to abut a diameter inside this deformable bead, as for example in the air suspension diaphragms described in the French Pat. No. 72.02268 or in the expansion sleeves described in French Pat. Nos. 2 280 853, 2 033 789 or 2 006 730.
These sleeve systems with flexible beads thus require mounting techniques which often cause a strong stress concentration at the end of the mating flange, which can go as far as damaging or even destroying the sealing function. Hence, the usual sleeves with flexible beads can only be used for moderate service pressures. To overcome these drawbacks, solutions of rigid sleeves with large contact areas with the flange have been proposed in, for example, U.S. Pat. No. 2,998,986. This is in fact the solution adopted by Kleber Industrie for its built-in pipe flanges, the Endflex system described in the Performer AD10 pipe catalog, page 4 or in its Dilatoflex K expansion sleeves described in catalog FC175-18, June 1984.
All these device have high rigidity and are usually built with metal elements. Because of their design, rubber is compressed over a large contact surface area which improves stress distribution and reduces creep sensitivity, thus providing a better guarantee of tightness and the possibility of utilization at high service pressures.
However, due to their rigidity, these beads have the drawback of making it impossible to mount one-piece mating flanges after manufacture of the sleeve. Hence it is necessary to mount said mating flanges during production and to vulcanize the sleeve thus equipped with these metal parts, which considerably augments the weight and volume.
In addition, mating flanges are no longer demountable as shown by the Stenflex and General Rubber catalogs. Thus, the sleeve manufacturer must keep a large inventory on hand so that sleeves equipped with flanges conforming to the various standardized connections are available.
A sleeve with demountable flanges is described in French Pat. No. 2447512 but the beads are rigid and have reinforcing collars separate from the sleeve. The proposed solution, which consists of surrounding the collar by a U-shaped rubber form, required a very complex mold to be built.
As can be seen from the above analysis, a solution conforming to the state of the art which enables the requirements of anchoring quality (to withstand high service pressures or pulls), tightness of bonding, and ease of mounting on a flange or rigid shoulder to be met, is not known.
Hence, the object of the invention is to provide an anchoring device which offers the advantages of the two types of known beads without suffering their disadvantages. The anchoring is obtained by a bead having a large contact surface on the flange or shoulder, while offering flexibility allowing bending for passage of the bead through the bore.
Thus, the invention permits simpler manufacture of the sleeve by eliminating the weight and volume problems engendered by the necessity (in previously known solutions) of mounting the mating flanges during manufacture. Moreover, and this represents an essential saving--it considerably reduces the need to maintain a large parts inventory due to the various connections since the same range of sleeves can be equipped with the various types of commercial or customized mating flanges at the time of delivery. Management and marketing of the sleeves is thus greatly facilitated and delivery times are considerably reduced.
The invention consists of a radial device for anchoring flexible tubular structures such as rubber hoses, deformable collars, expansion joints, and suspension diaphragms in an opening in a rigid wall by abutting a shoulder or flange after passing through an opening or hole in said rigid wall, characterized by the flexible tubular structure, or sleeve, having at least one bead reinforced by a fragmented armature embedded in the rubber, composed of independent rigid elements to allow the bead to bend so it can slide into the bore of the rigid wall without altering, after a return to the plane shape, the radial rigidity which confers on the bead the necessary strength for its proper operation in service when it is compressed between the flange and the mating flange.
The essential element of the invention is comprised of the fragmented bead-reinforcing armature, formed of a metal or plastic hoop with high rigidity, composed of elements with varied geometric shapes, independent of each other.
At the time the sleeve is manufactured, it is necessary to position the elements of the fragmented armature in the mold and, such positioning operation may be accomplished in several ways such as, for example, by placing the individual elements in the mold itself or, in a premanufacturing phase, by disposing the element on a support comprising a layer of rubber-based mixture, with or without a textile base.
In all cases, a space, generally between 0.5 and 50% of the width of an element of the fragmented armature, will be left free between two adjacent elements for "rubber bridges" to be created, i.e. physical and chemical links between the rubber-based mixtures located in the mold above and below the fragmented armature in order to achieve the capability of radial mechanical bending of the bead upon mounting in the connecting mating flange.
At the time the sleeve is made, the fragmented armature can be placed in the bead either bare or wrapped in a ply of rubber mixture or of a fine textile material, the latter two possibilities having the advantage of protecting the carcass of the sleeve from damage when it contacts the edges of the fragmented armature.
The individual elements, whether or not they adhere to one another, embedded in the rubber, after vulcanization form an armature rendering the bead rigid, due to the high compression ridigity of the "rubber bridges" cited above.
However, these individual elements articulate with each other without damaging the reinforcing carcass of the sleeve and permit the bead to pass into the bore when the bead, which has become flexible is bent, whereby the bead re-opens on the shoulder naturally after the mating flanges have been put in place. The bead, wedged between the connecting flange and the mating flange or the shoulder, retains a radial rigidity equivalent to that of a bead with a one-piece armature by the self-pinching effect.
The fragmented armature is preferably made of a metal such as steel, aluminum, Zamak, or any other material (reinforced or composite plastic) whose tensile modulus is greater than 1500 MPa.
The number of individual elements of which the fragmented armature is composed is preferably between seven and thirteen, but it can be as great as the strength of the material and manufacturing economics permit.
The general shape of the individual elements is usually trapezoidal, but other possibilities may be considered such as rectangular, triangular, lozenge, or double trapezoidal shapes, cited as nonlimitative examples, which shapes would complicate the manufacturing of the fragmented armature elements but would not harm their operation. The separating zones between the individual elements are generally oriented radially but the reinforcement function is not harmed if the separating zones have a slight inclination, between 0.degree. and 40.degree., with respect to a radius of the annular armature which crosses the separating zone.
The separating zones between the individual elements of the armature are rectilinear in the most frequent case but may have the shapes of arcs of circles, any curves, or chevrons.